Nanometer-scale crossed-wire switching devices have previously been reported that could be switched reversibly and had an ON-to-OFF conductance ratio of about 103. Such devices have been used to construct crossbar circuits and provide a promising route for the creation of ultra-high density nonvolatile memory. A latch (which is an important component for logic circuits and for communication between logic and memory) has been fabricated from a series connection of crossed-wire switches. New logic families, constructed entirely from crossbar arrays of switches or as hybrid structures composed of switches and transistors, have also been described. These new logic families have the potential to dramatically increase the computing efficiency of CMOS circuits.